Power driven grass shear

ABSTRACT

A shear for grass and the like includes a tooth plate on which is pivotally mounted a plurality of shearing members, each including a narrow and resiliently deformable blade element. The blade elements extend outwardly along the upper surface of the tooth plate, and each oscillates across one of the cutting recesses that are defined between adjacent teeth at one end of the plate. The outer ends of the blade elements are biased toward the tooth plate causing substantially point contact to exist between the cutting edges of the blade element and the side edges of the teeth as the blade elements wipe thereover. Preferably, the shear is power driven, and most desirably energy is supplied by a battery housed within the body thereof.

United States Patent Ketchpel, Jr. et al.

[ POWER DRIVEN GRASS SHEAR [75] Inventors: Paul A. Ketchpel, Jr.,Simsbury;

Carl C. Stoutenberg, Avon; Edward J. Johnson, New Britain, all of Conn.

[73] Assignee: The Stanley Works, New Britain, Conn.

22 Filed: Jan. 4, 1972 21 Appl. No; 215,358

[52] US. Cl 30/210, 30/216, 30/218, 30/222, 30/233, 30/236, 30/247 [51]Int. Cl. B26b 19/12 [58] Field of Search 30/197, 210, 216,

[ 51 Nov. 27, 1973 Dutcher 30/228 Walton 30/210 57 ABSTRACT A shear forgrass and the like includes a tooth plate on which is pivotally mounteda plurality of shearing members, each including a narrow and resilientlydeformable blade element. The blade elements extend outwardly along theupper surface of the tooth plate, and each oscillates across one of thecutting recesses that are defined between adjacent teeth at one end ofthe plate. The outer ends of the blade elements are biasedtoward thetooth plate causing substantially point contact to exist between thecutting edges of the blade element and the side edges of the teeth asthe blade elements wipe thereover. Preferably, the shear is powerdriven, and most desirably energy is supplied by a battery housed withinthe body thereof.

17 Claims, 8 Drawing Figures Patented Nov. 27, 1973 2 Sheets-Sheet lFIG.2

lllllllllmumuu FICxB Patented Nov. 27, 1973 3,774,302

2 Sheets-Sheet 2 1 POWER DRIVEN'GRASS SHEAR BACKGROUND OF THE INVENTIONPower driven grass shears, hedge trimmers and similar tools of the priorart have typically employed moving parts or relatively large mass andhave been designed with rather extensive areas of contact betweenshearing elements. These factors, which in many cases are augmented bythe biasing of parts with separate springs and the like to improve theshearing effect, are responsible for creating considerable levels ofdrag or frictional resistance to movement in such tools. In addition tofunctional resistance, inertia is another significant factor in thepower requirements for operation. These and other factors are especiallysignificant in de vices of this sort that are designed for battery poweroperation because the weight added by the battery will generally beproportional to the energy demands of the tool.

Sharpening or reconditioning of the blades of such prior art tools isoften difficult and inconvenient because of the extent to which the toolmust be disassembled for removal of the blade. Moreover, the rathercomplex configuration that is typical of such blades makes it quitedifficult to create or sharpen the cutting edges by a hollow grinding orsimilar conventional technique, and the cost of replacing such a bladeafter it has worn out may often be prohibitive.

- Accordingly, it is an object of the present invention to provide anovel shear for grass and the like which opcrates highly efficientlywith relatively low power, which employs moving parts that arerelatively light weight and few in number, and which is relativelysimple and inexpensive to manufacture.

A more specific object of the invention is to provide such a novel shearin which frictional resistance and inertia are minimized.

Another object is to provide a shear of the foregoing type in whichvibration is minimized and safety is maximized by virtue of a low stalltorque characteristic.

Still another object is to provide such a shear in which the bladeelements employed are relatively inexpensive and are readily removed forreplacement or reconditioning.

A further object is to provide a novel power driven shear having all ofthe foregoing features and advantages and designed for self-containedbattery-powered operation.

SUMMARY OF THE DISCLOSURE It has now been found that the foregoing andrelated objects of the invention may be readily attained in a shearincluding a generally planar tooth plate and a plurality of shearingmembers, the tooth plate having at one end thereof a multiplicity oftooth formations defining generally U-shaped cutting recessestherebetween. Each of the shearing members has a relatively narrow andresiliently deformable blade element extending outwardly along the uppersurface of the end of the tooth plate, and each of the blade elementshas cutting edges extending along both side margins of the outer endportion thereof. The shearing members are pivotally mounted in the shearinwardly from the one end of the tooth plate for movement across one ofthe cutting recesses. The outer end portions of the blade elements areresiliently biased against the upper surface of the tooth plate, andeach is oscillatable across the aligned cutting recess with the cuttingedges thereof wiping the side edges of the tooth formations defining therecess. Drive means oscillates the shearing members upon the toothplate, with the bias thereof tending to urge the outer portions of theblade elements through the cutting recesses. This causes substantiallypoint contact to occur between the cutting edges and the side edges ofthe blade elements wipe the tooth formations in a scissors-like fashion.

The shearing members are preferably independently mounted. Mostdesirably, they are mounted on the tooth plate'to oscillate in asubstantially parallel relationship to one another with the point ofpivotal mounting for each of the shearing members advantageously beingin substantial alignment with the axis of the cutting recess acrosswhich it moves. The points of attachment of the shearing members to thedrive means may be spaced above the upper surface of the tooth plate toelevate the shearing members thereabove. This will tend to minimize thearea of contact between the tooth plate and the shearing members andwill enhance the shearing effect of the cutting edges of the bladeelements.

Preferably, each of the shearing members comprises a blade carrier whichis pivotally mounted upon the tooth plate, and an independent bladeelement disengageably supported thereby. The blade carrier may desirablybe elongated with means adjacent one end for engaging the independentblade element. Both the carrier and also the blade element may besubstantially rectilinear, and the carrier may be mounted upon the toothplate with the axis thereof substantially parallel to the upper surfaceof the plate and with the engaging means supporting the blade element atan angle to the carrier, thus disposing the blade element downwardlytherefrom toward the tooth plate. Most desirably, the one end of thecarrier will have a slot extending therethrough with a tang portionadjacent one end of the independent blade element being insertedupwardly through the slot and retained therein to engage and dispose theblade element as described. A pin may be affixed on either the carrieror the tang of the blade element and secured in an aperture provided inthe other one thereof. The pin may be disposed with its axissubstantially perpendicular to the axisof the blade element, with thebias of the shear member urging the pin into the aperture to preventinadvertent disassembly thereof.

The shear may additionally include a sole plate element extending alongthe lower surface of the tooth plate and substantially across the toothplate adjacent the inner ends of the tooth formations to space the toothformations upwardly from surfaces over which the shear is operated. Thiswill prevent excessive wear and damage to the tooth formations clue tocontact therewith. Preferably, the sole plate element will underlie theinner end portions of the recesses between the tooth formations and willprovide web portions having edge surfaces extending transverselytherebetween. The web portions reduce the effective depth of the toothformations and blade elements exposed for cutting and support the bladeelements during oscillation between the side edges of the toothformations, thereby facilitating movement thereof.

In the preferred embodiments of the invention the drive means for theshear includes an electric motor to render it power driven, and mostdesirably a battery to provide energy for the motor is additionallyincluded. The drive means may also include a gear in driven engagementwith the motor and having an axially projecting cam elementeccentrically disposed on one side thereof. in such a case, the drivemeanswill additionally include a cam follower member having a camsurface extending parallel to the cam element of the,

driven gear for contact therewith, and configured to impart oscillatorymovement to the follower movement upon rotation of the gear with the camelement contacting the cam surface. With the shearing members pivotallyconnected to the cam follower member, contact of the cam element on thecam surface translates rotary motion of the gear to oscillatory movementof the follower member in a substantially parallel plane, the followermember in turn imparting oscillation to the shearing members.Preferably, the follower member has an elongated opening thereinproviding the cam surface, the opening having its longitudinal axissubstantially parallel to the direction of extension of the toothformations of the tooth plate. Most desirably, the cam element has agenerally circular transverse cross sectional configuration and theopening of the follower member has substantially rectilinear sidemargins, such margins extending parallel to the longitudinal axis of theopening and spaced therefrom a distance substantially equal to theradius of the cam element.

In most instances, the shear will include a housing which may enclosethe motor as well as a battery. In such a case the tooth plate mayextend outwardly from one end of the housing and the housing may have ahandle portion extending from the other end thereof in a directiongenerally opposite to that in which the tooth plate extends.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 of the drawings is a sideelevational view of a power driven shear embodying the presentinvention;

FIG. 2 is a side elevational view of the operating components in theforward portion of the shear of FIG. 1 drawn to an enlarged scale;

FIG. 3 is an exploded side elevational view of the gear and cammechanism providing oscillatory motion to the cutting blades of theshear;

FIG. 4 is a sectional view of the shear along the line 4--4 of FIG. 2,with the drive gear broken away to show the associated eccentric lobeand with the parallel cutting blades in a neutral position;

FIG. 5 is a sectional view along the line 5--5 of FIG. 2, with theeccentric lobe displaced by a quarter revolution of the drive gear fromits position in FIG. 4 and with the blades shifted thereby to a positionat the end of a cutting stroke in one direction during the cycle ofoperation;

FIG. 6 is an exploded perspective view of the shearing member assemblyprovided by the cutting blade and carrier illustrated in previousfigures;

FIG. 7 is a sectional view of the forward end portion of the carrieralong the line 77 of FIG. 6 drawn to a further enlarged scale; and

FIG. 8 is a sectional view of one of the blades and the center tooth ofthe tooth plate along the line 8-8 of FIG. 6 and illustrating the crosssectional configurations thereof.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT Turning now in detailto the appended drawings, therein illustrated is a power driven grassshear em bodying the present invention and including a molded housinggenerally designated by the numeral 10 and having a hand grip portion12, a body portion 13 and a grip reinforcing portion 11. The bodyportion 13 encloses an electric motor 14 and the reinforcing portion 11encloses a rechargeable battery 16 and recharging means (not shown). Themotor 14 and battery 16 are electrically interconnected by conventionalmeans with a switch 18 (only the toggle of which is illustrated) beingprovided in the circuit to control operation of the shear. A housingblock or shoe 20 is provided at the lower end of the body portion 13,and a tooth plate or comb 22 extends along the lower surface of theblock 20, forwardly and outwardly from the housing 10. The housing block20 is configured to accommodate and enclose various parts of the shear.

As may best be seen in FIGS. 4 and 5, the tooth plate 22 has atridentate forward configuration with a symmetrical pointed center tooth24 and with teeth 26 spaced to either side thereof. The center tooth 24has a bevelled face 28 along the underside of each of its two sidemargins providing cutting edges thereat, and each of the side teeth 26has a similar face 28 along the underside of its inner side margin toprovide comparable cutting edges 31 thereon. The edges 29,31 of adjacentteeth 26,24 respectively converge inwardly and in part define cuttingrecesses therebetween.

Fixed against the underside of the tooth plate 22, by welding or othermeans, is a sole plate 30 which extends transversely across the forwardportion of the tooth plate 22 and provides-web portions 32 between theteeth 24,26 thereof. In general, the sole plate 30 serves to minimizewear and damage from contact that would otherwise occur on surfacesover' which the shear is operated; however,.it will be appreciated thatthe forward edges 33 thereof cooperate with the edges 29,3] of the teeth24,26 in defining the cutting recesses therebetween. At four locationsabout the periphery of the tooth plate 22 mounting apertures 34 areprovided, and a pair of pivot post apertures 36 are also formedtherethrough to permit mounting of the dual cutting mechanism of theshear.

Extending from the motor 14 is a vertical shaft 38 with a drive pinion40 which meshes with a relatively large driven gear 42, at the undersideof which is affixed or integrally formed an eccentric lobe or cam 44.The gear 42 and lobe 44 are mounted upon a vertical shaft 46, which isjoumalled in an aperture in the block 20 (as is seen in FIG. 2).

Each of a pair of elongated and relatively narrow blade carriersgenerally designated by the numeral 48 is pivotally mounted upon adouble-headed rivet or pivot post 52, the rivets pass through pivotapertures 50 in the central portion 49 of the carriers 48 and throughthe pivot post apertures 36 in the tooth plate 22 to mount the carriers48 thereon. Since each of the carriers 48 is of identical construction,only one of them need be described in detail hereinafter.

An axial inner arm portion 54 extends outwardly from the central portion49 of the carrier 48 and has a pivot aperture 56 at its end. A pivotmember 58 passes upwardly through the pivot aperture 56 and is engagedin the aperture 59 in one of the ear portions 61 of the yoke or camfollower 60, the pivot members 58 being pivotably seated in one or bothmembers to permit relative pivoting to occur between the yoke 60 and thecarriers 48 attached thereto. Since the spacing between the pivot post52 and between the apertures 59 in the ear portions 61 is substantiallyequal, the two shean'ng members will oscillate in general parallelism,as is seen in FIGS. 4 and 5. The yoke 60 has a central opening 62 ofgenerally oval configuration, in which is seated the lobe 44 present onthe underside of the drive gear 42. The opening 62 is defined byparallel rectilinear side surfaces 65, and is of a length which isadequate to accommodate the lobe 44 in either the position shown in FIG.4 or in the diametrically opposed position which would result fromrotation of the gear 42 through an angle of 180 degrees therefrom. Ascan be seen, the spacing between the surfaces 65 is substantially equalto the diameter of the lobe 44 to achieve a close fit, which will ensuresmooth operation and will minimize chatter.

' In the slightly tapered forward arm portion 63 of the carrier 48 is arectangular axially elongated slot 64 which is defined at its forwardend by the bridge portion 66 at the outer end of the carrier 48. As isbest seen in FIG. 7, the underside of the bridge portion 66 has adownwardly and forwardly sloping channel 68 of generally Ushapedtransverse cross section, which leads into the forward end of therectangular slot 64. A similar channel 70 of generally U-shaped crosssection is provided in the upper surface of the carrier 48 and slopesupwardly and inwardly from the rear of the rectangular slot 64 atsubstantially the same angle of incline as the channel 68. A shorttilted pin 72 is seated in an aperture 73 of the carrier 48 and extendsupwardly from the sloping floor of the channel 70 at an angle of about90 degrees thereto. The channels 68,70 are dimensioned and configured toreceive therein, in closefitting engagement along its sides, theelongated tang 78 of a cutting blade 74, which is slightly narrower thanthe slot 64 of the carrier 48 to provide clearance for facility ofassembly and disassembly.

As can be seen from the drawings, the blade 74 is assembled with thecarrier 48 by inserting the tang 78 thereof upwardly through the slot 64and with the tilted pin 72 is engaged in the aperture 80 in the innerend thereof. This positions the blade 74 at a slight downward angle tothe axis of the carrier 48 and, since the carrier 48 extends generallyparallel to the plane of the tooth plate 22, the blade 74 also extendsdownwardly relative thereto. As seen in FIG. 8, the cutting faces 76along each side margin of the forward portion of the blades 74 aretypically ground, conveniently at an angle of about 45 degrees, and thecutting edges defined thereby cooperate with the cutting edges 29,31 ofthe teeth 24,26 in a manner more fully described hereinafter, the faces28 of the teeth 24,26 typically being provided with a 12 degree bevel.

In operation, the motor 14 rotates the pinion 48 which is rigidlyaffixed to the shaft 38 thereof; meshing engagement of the pinion 40rotates the driven gear 42 which, in turn, moves the lobe 44 in acircular path about the shaft 46. This movement shifts the yoke 60 backand forth across the rear portion of the tooth plate 22, causing the twoblade carriers 48 to pivot about the rivets or pivot posts 52, in turnoscillating the blades, 74 within the cutting recesses defined by theteeth 24,26

and the web portions 32. In FlG. 4, the blades 74 are in small areacontact with the edges of the tooth plate 22 at the inner end of thecutting recesses. As the mechanism is shifted to the position shown inFIG. 5, the blades 74 move across these edges and then encounter theedges 31,29 of the teeth 24,26 where the forward edge moves therealongin a substantially point contact relationship. High levels of shearforce are thereby developed between the cutting edges defined by theteeth 24,26 and the blades 74, causing clean and highly efficientshearing of blades of grass present therebetween. The sole plate 30provides clearance for the blades 74 and affords additional protectionby minimizing the exposed tooth depth.

As can best be seen in FIG. 2, the construction of the present shearresults in a minimum amount of contact between the relatively movingparts thereof. Thus, due to the downward bias of the blades 74,frictional resistance to oscillation is present at only the line orpoint of contact with the edges of the tooth plate 22 at the inner endof the cutting recesses and with the cutting edges 28 of the teeth24,26. The only other points of contact for the oscillating cutterassembly, comprised of a carrier 48 and blade 74, are at the head of thepivot member 58 and at the pivot post 52. This is in contrast tocomparable prior art devices in which contact normally occurs over mostof one surface of a relatively large movable cutting member, andminimization of the area of contact is further enabled by fastening thearm portion 54 of the carrier 48 to the yoke 60 above the plate 22 inthe manner illustrated.

The narrow and relatively thin configuration of the carriers 48 andblades 74 minimizes the mass and resulting inertia of reciprocatingparts, thereby reducing the power requirements for the shear and itslevel of vibration, while at the same time enhancing safety by enablinga low stall torque characteristic. The relative flexibility or resilientdeformability of the blades 74 and their individual mountings permitthem to closely follow the contour of the teeth 24,26 independently ofone another and to flex and twist as necessary to ride upon the edgesthereof in such a manner as to produce a very efficient wiping sheareffect.

Moreover, the blades 74 are individually removable with great facilityfor replacement or sharpening, and their construction makes theminherently inexpensive, both in material costs and in permitting the useof conventional and facile straight edge sharpening techniques. Bladesof the sort illustrated can be produced from long lengths of steel stripthat have been hollow ground along their edges, and reconditioning ofdull blades can readily be accomplished with common household sharpeningimplements if so desired.

Since it is the bias of the blades 74 which holds them in engagement onthe pins 72, to remove a blade it is only necessary to lift theassociated carrier 48 slightly to relieve the biasing force. The blade74 can then be tilted downwardly to disengage the pin 72 from theaperture of the tang 78, enabling ready removal from the slot 64.

Although not illustrated, it should be appreciated that the entireshearing member may be provided by an elongated and flexible blade ofappropriate dimensions, and that it is not necessary that the shearemploy the carrier/blade assembly type of shearing member shown. Thus, ablade of a length equivalent to the assembly and having appropriateapertures to receive the pivot post 52 and fastener 58 may besubstituted, but in such an instance the blade should itself have adecided curvature or bow to ensure that a downward bias is produced atits free end (such a blade curvature may also be desirable in some casesin which an assembly is employed). In addition, this alternative issomewhat less desirable due to the lessened facility with which theblades may be removed and changed.

Although two blades normally will be employed, in some instances threeor more blades may be found beneficial albeit with increased weight andpower require-.

ments. It should be appreciated that, although the advantages of theinvention are most significant when the shear is power driven and thatsuch devicesconstitute the preferred embodiments hereof, the drivingmeans may simply be a mechanism enabling manual operation of the tool,with the relatively low levels of friction, light weight, and facilityof blade replacement being of considerable advantage in such a handoperated shear.

The materials of construction will be readily apparent to those skilledin the art and need not be described in detail herein. However, theblades are produced of hardened steel and may be coated with a syntheticmaterial having a low coefficient of friction such as apolytetrafluoroethylene type of resin to even further reduce friction.As is now conventional in such devices, synthetic plastic constructionmay be employed for the housing parts and for gears and the like toafford quiet and trouble-free operation over long periods of use,although aluminum and/or other metals may be preferred for certain partsin some instances. Fiber reinforced plastics and the engineering resinssuch as polyacetals, polyamides, etc. are desirably utilized.

Although the tooth plate and sole plate are shown as separate elementsin the attached drawings, it will be appreciated that they may beintegrally formed. Simi larly, the housing may be configured and formedwith the housing block as an integral extension of the body portion 13,convenienty as a clam-shell type of construction for ease offabrication.

Thus, it can be seen that the present invention provides a novel shearfor grass and the like which operates highly efficiently with relativelylow power, which employs moving parts that arerelatively lightweight andfew in number, and which is relatively simple and inexpensive tomanufacture. More specifically, the invention provides a novel shear inwhich frictional resistance and inertia are minimized and in whichsafety is maximized by virtue of a low stall torque characteristic. Theblade elements employed are relatively inexpensive and are readilyremoved for replacement and re conditioning. The present construction isparticularly well suited for use to provide a power driven shear, andparticularly one designed for self-contained batterypowered operation.

We claim:

1. In a shear, the combination comprising:

a. a generally planar tooth plate having at one end thereof amultiplicity of tooth formations defining generally U-shaped cuttingrecesses therebetween;

b. a plurality of shearing members each having a relatively narrow andresiliently deformable blade element extending outwardly'along the uppersurface of said one end of said tooth plate and having cutting edgesextending along both side margins of the outer end portion thereof, eachof said shearing members being individually pivotally mounted on saidtooth plate inwardly from said one end thereof for movement across oneof said cutting recesses, said shearing members extending in spacedrelationship from the surface of said tooth plate over substantially theentire length thereof inwardly of the point of pivotal mounting thereof,said outer end portion of said blade element thereof being re silientlybiased against said surface of said tooth plate and being oscillatableacross the aligned cutting recess with said cutting edges thereof wipingthe side edges of the tooth formations defining said recess; and

drive means for oscillating said shearing members upon said tooth plate,said shearing members being attached adjacent their inner ends to saiddrive means at a point spaced above said upper surface of said toothplate, said drive means tending to elevate said shearing members abovesaid upper surface to minimize the area of contact therebetween and toenhance the shearing efiect of said cutting edges of said bladeelements, the bias of said shearing members tending to urge said outerend portions of said blade elements thereof through said cuttingrecesses and causing substantially point contact between said cuttingedges and said side edges as said blade elements wipe said toothformations.

2. The shear of claim 1 wherein said drive means includes an electricmotor to render said shear power driven.

3. The shear of claim 2 additionally including a battery to provideenergy for said motor.

4. The shear of claim 2 wherein said drive means includes a gear indriven engagement with said motor and having an axially projecting camelement eccentrically disposed on one side thereof, and a cam followermember having a cam surface extending parallel to said cam element forcontact therewith and configured to impart oscillatory movement to saidfollower member upon rotation of said gear with said cam elementcontacting said cam surface, said shearing members being pivotallyconnected to said cam follower member and said cam element contactingsaid cam surface to translate rotary motion of said gear to oscillatorymovement of said follower member in a substantially parallel plane,which in turn imparts said oscillation to said shearing members.

5. The shear of claim 4 wherein said follower member has an elongatedopening therein providing said cam surface, said opening having itslongitudinal axis substantially parallel to the direction of extensionof said tooth formations of said tooth plate.

6. The shear of claim 5 wherein said cam element has a generallycircular transverse cross sectional configuration, and wherein saidopening has substantially rectilinear side margins extending parallel tosaid longitudinal axis of said opening and spaced therefrom a distancesubstantially equal to the radius of said cam element.

.7. The shear of claim 4 wherein said shearing members are substantiallyrectilinear and are attached to said cam follower member with aspacingtherebetween substantially equal to the distance between said axes ofpivotal mounting thereof in said shear, therebydisposing said shearingmembers in a substantially parallel relationship and constraining themto parallelism during oscillation.

8. The shear of claim 4 wherein said drive means is positioned adjacentthe other end of said tooth plate, said cam follower member beingpositioned adjacent said upper surface of said tooth plate with saidshearing members attached thereto adjacent their inner ends and withsaid gear being positioned above said follower member with said camelement thereof extending downwardly thereto, said motor beingpositioned with its drive shaft extending downwardly along an axisparallel to that of said gear and having affixed thereon a pinion inmeshing engagement therewith.

9. The shear of claim 3 additionally including a housing enclosing saidmotor and battery, said tooth plate extending outwardly from one end ofsaid housing and said housing having a handle portion extending from theother end thereof in a direction generally opposite to that in whichsaid tooth plate extends.

10. In a shear, the combination comprising:

a. a generally planar tooth plate having at one end thereof amultiplicity of tooth formations defining generally U-shaped cuttingrecesses therebetween;

b. a plurality of shearing members each comprised of a blade carrierindividually pivotally mounted on said tooth plate inwardly from saidone end thereof and a relatively narrowand resiliently deformableindependent blade element extending outwardly along the upper surface ofsaid one end of said tooth plate and having cutting edges extendingalong both side margins of the outer end portion thereof, said bladecarrier having means thereon adjacent the outer end disengageablymounting said independent blade element with the outer end portion ofsaid blade element being resiliently biased against said surface of saidtooth plate, said shearing members being oscillatable about the pivotalmounting of said blade carriers to oscillate said blade elements acrossthe aligned cutting recesses with said cutting edges thereof wiping theside edges of the tooth formations defining said recess; and

drive means for oscillating said shearing member upon said tooth plate,the bias of said blade elements tending to urge said outer end portionsthereof through said cutting recesses and causing substantially pointcontact between said cutting edges and said side edges as said bladeelements wipe said tooth formations.

11. The shear of claim 10 wherein said shearing members are mounted onsaid tooth plate to oscillate in a substantially parallel relationshipto one another, and wherein the point of pivotal mounting for each ofsaid shearing members is in substantial alignment with the axis of saidone cutting recess across which it moves.

12. The shear of claim 10 wherein said blade carrier is elongated, andwherein both said carrier and said blade element are substantiallyrectilinear, said carrier being mounted upon said tooth plate with theaxis thereof substantially parallel to said upper surface of said plate,said mounting means supporting said blade element at an angle to saidcarrier disposing said blade element downwardly therefrom toward saidtooth plate.

13. The shear of claim 12 wherein said one end of said carrier has aslot extending therethrough, a tang portion adajcent one end of saidindependent blade element being inserted upwardly through said slot andretained therein to so engage and dispose said blade element.

14. The shear of claim 14 wherein said blade element is retained by apin affixed on one of said carrier and said tang of said blade element,the other of said carrier and tang having said pin securely received inan aperture thereof dimensioned and configured therefor, said pin beingdisposed with its axis substantially perpendicular to the axis of saidblade element and said bias of said shear member urging said pin intosaid aperture to prevent inadvertent disassembly thereof.

15. In a shear, the combination comprising:

a. a generally planar tooth plate having at one end thereof amultiplicity of tooth formations defining generally U-shaped cuttingrecesses therebetween;

b. a plurality of shearing members each having a relatively narrow andresiliently deformable blade element extending outwardly along the uppersurface of said one end of said tooth plate and having cutting edgesextending along both side margins of the outer end portion thereof, eachof said shearing members being pivotally mounted in said shear inwardlyfrom said one end of said tooth plate for movement across one of saidcutting recesses, said outer end portion of said blade element thereofbeing resiliently biased against said surface of said tooth plate andbeing oscillatable across the aligned cutting recess with said cuttingedges thereof wiping the side edges of the tooth formations definingsaid recess; a sole plate element extending the lower surface of saidtooth plate substantially across said tooth plate adjacent the innerends of said tooth formations thereof to space said tooth formationsupwardly from surfaces over which the shear is operated and therebyprevent excessive wear and damage to said tooth formations due tocontact therewith; and

(1. drive means for oscillating said shearing member upon said toothplate, the bias of said shearing members tending to urge said outer endportions of said blade elements thereof through said cutting recessesand causing substantially point contact be tween said cutting edges andsaid side edges as said blade elements wipe said tooth formations. 16.The shear of claim 15 wherein said shearing members are individuallymounted. 17. The shear of claim 15 wherein said sole plate elementunderlies the inner end portions of the recesses between said toothformations and provides web portions having edge surfaces extendingtransversely between said tooth formations, said web portions reducingthe effective depth of said tooth formations and blade elements exposedfor cutting a: a:

1. In a shear, the combination comprising: a. a generally planar toothplate having at one end thereof a multiplicity of tooth formationsdefining generally U-shaped cutting recesses therebetween; b. aplurality of shearing members each having a relatively narrow andresiliently deformable blade element extending outwardly along the uppersurface of said one end of said tooth plate and having cutting edgesextending along both side margins of the outer end portion thereof, eachof said shearing members being individually pivotally mounted on saidtooth plate inwardly from said one end thereof for movement across oneof said cutting recesses, said shearing members extending in spacedrelationship from the surface of said tooth plate over substantially theentire length thereof inwardly of the point of pivotal mounting thereof,said outer end portion of said blade element thereof being resilientlybiased against said surface of said tooth plate and being oscillatableacross the aligned cutting recess with said cutting edges thereof wipingthe side edges of the tooth formations defining said recess; and c.drive means for oscillating said shearing members upon said tooth plate,said shearing members being attached adjacent their inner ends to saiddrive means at a point spaced above said upper surface of said toothplate, said drive means tending to elevate said shearing members abovesaid upper surface to minimize the area of contact therebetween and toenhance the shearing effect of said cutting edges of said bladeelements, the bias of said shearing members tending to urge said outerend portions of said blade elements thereof through said cuttingrecesses and causing substantially point contact between said cuttingedges and said side edges as said blade elements wipe said toothformations.
 2. The shear of claim 1 wherein said drive means includes anelectric motor to render said shear power driven.
 3. The shear of claim2 additionally including a battery to provide energy for said motor. 4.The shear of claim 2 wherein said drive means includes a gear in drivenengagement with said motor and having an axially projecting cam elementeccentrically disposed on one side thereof, and a cam follower memberhaving a cam surface extending parallel to said cam element for contacttherewith and configured to impart oscillatory movement to said followermember upon rotation of said gear with said cam element contacting saidcam surface, said shearing members being pivotally connected to said camfollower member and said cam element contacting said cam surface totranslate rotary motion of said gear to oscillatory movement of saidfollower member in a substantially parallel plane, which in turn impartssaid oscillation to said shearing members.
 5. The shear of claim 4wherein said follower member has an elongated opening therein providingsaid cam surface, said opening having its longitudinal axissubstantially parallel to the direction of extension of said toothformations of said tooth plate.
 6. The shear of claim 5 wherein said camelement has a generally circular transverse cross sectionalconfiguration, and wherein said opening has substantially rectilinearside margIns extending parallel to said longitudinal axis of saidopening and spaced therefrom a distance substantially equal to theradius of said cam element.
 7. The shear of claim 4 wherein saidshearing members are substantially rectilinear and are attached to saidcam follower member with a spacing therebetween substantially equal tothe distance between said axes of pivotal mounting thereof in saidshear, thereby disposing said shearing members in a substantiallyparallel relationship and constraining them to parallelism duringoscillation.
 8. The shear of claim 4 wherein said drive means ispositioned adjacent the other end of said tooth plate, said cam followermember being positioned adjacent said upper surface of said tooth platewith said shearing members attached thereto adjacent their inner endsand with said gear being positioned above said follower member with saidcam element thereof extending downwardly thereto, said motor beingpositioned with its drive shaft extending downwardly along an axisparallel to that of said gear and having affixed thereon a pinion inmeshing engagement therewith.
 9. The shear of claim 3 additionallyincluding a housing enclosing said motor and battery, said tooth plateextending outwardly from one end of said housing and said housing havinga handle portion extending from the other end thereof in a directiongenerally opposite to that in which said tooth plate extends.
 10. In ashear, the combination comprising: a. a generally planar tooth platehaving at one end thereof a multiplicity of tooth formations defininggenerally U-shaped cutting recesses therebetween; b. a plurality ofshearing members each comprised of a blade carrier individuallypivotally mounted on said tooth plate inwardly from said one end thereofand a relatively narrow and resiliently deformable independent bladeelement extending outwardly along the upper surface of said one end ofsaid tooth plate and having cutting edges extending along both sidemargins of the outer end portion thereof, said blade carrier havingmeans thereon adjacent the outer end disengageably mounting saidindependent blade element with the outer end portion of said bladeelement being resiliently biased against said surface of said toothplate, said shearing members being oscillatable about the pivotalmounting of said blade carriers to oscillate said blade elements acrossthe aligned cutting recesses with said cutting edges thereof wiping theside edges of the tooth formations defining said recess; and c. drivemeans for oscillating said shearing member upon said tooth plate, thebias of said blade elements tending to urge said outer end portionsthereof through said cutting recesses and causing substantially pointcontact between said cutting edges and said side edges as said bladeelements wipe said tooth formations.
 11. The shear of claim 10 whereinsaid shearing members are mounted on said tooth plate to oscillate in asubstantially parallel relationship to one another, and wherein thepoint of pivotal mounting for each of said shearing members is insubstantial alignment with the axis of said one cutting recess acrosswhich it moves.
 12. The shear of claim 10 wherein said blade carrier iselongated, and wherein both said carrier and said blade element aresubstantially rectilinear, said carrier being mounted upon said toothplate with the axis thereof substantially parallel to said upper surfaceof said plate, said mounting means supporting said blade element at anangle to said carrier disposing said blade element downwardly therefromtoward said tooth plate.
 13. The shear of claim 12 wherein said one endof said carrier has a slot extending therethrough, a tang portionadajcent one end of said independent blade element being insertedupwardly through said slot and retained therein to so engage and disposesaid blade element.
 14. The shear of claim 14 wherein said blade elementis retained by a pin affixed on one of said carrier and said tang ofsAid blade element, the other of said carrier and tang having said pinsecurely received in an aperture thereof dimensioned and configuredtherefor, said pin being disposed with its axis substantiallyperpendicular to the axis of said blade element and said bias of saidshear member urging said pin into said aperture to prevent inadvertentdisassembly thereof.
 15. In a shear, the combination comprising: a. agenerally planar tooth plate having at one end thereof a multiplicity oftooth formations defining generally U-shaped cutting recessestherebetween; b. a plurality of shearing members each having arelatively narrow and resiliently deformable blade element extendingoutwardly along the upper surface of said one end of said tooth plateand having cutting edges extending along both side margins of the outerend portion thereof, each of said shearing members being pivotallymounted in said shear inwardly from said one end of said tooth plate formovement across one of said cutting recesses, said outer end portion ofsaid blade element thereof being resiliently biased against said surfaceof said tooth plate and being oscillatable across the aligned cuttingrecess with said cutting edges thereof wiping the side edges of thetooth formations defining said recess; c. a sole plate element extendingthe lower surface of said tooth plate substantially across said toothplate adjacent the inner ends of said tooth formations thereof to spacesaid tooth formations upwardly from surfaces over which the shear isoperated and thereby prevent excessive wear and damage to said toothformations due to contact therewith; and d. drive means for oscillatingsaid shearing member upon said tooth plate, the bias of said shearingmembers tending to urge said outer end portions of said blade elementsthereof through said cutting recesses and causing substantially pointcontact between said cutting edges and said side edges as said bladeelements wipe said tooth formations.
 16. The shear of claim 15 whereinsaid shearing members are individually mounted.
 17. The shear of claim15 wherein said sole plate element underlies the inner end portions ofthe recesses between said tooth formations and provides web portionshaving edge surfaces extending transversely between said toothformations, said web portions reducing the effective depth of said toothformations and blade elements exposed for cutting